Numerical analysis of CaCO3 deposition effects on heat exchanger thermal performance

The deposition of CaCO3 on heating surfaces significantly reduces the thermal efficiency of heat exchangers and increased energy losses. This study investigates a microtube heat exchanger designed for lithium-ion battery water cooling systems. A numerical investigation is conducted using the Eulerian-Lagrangian approach to evaluate the degradation of thermal performance and energy loss caused by the deposition of submicron particles on heating surfaces. The study considers laminar flow in a pipe with a constant surface heat flux. The discrete element method (DEM) is employed to model particle deposition dynamics, while Computational Fluid Dynamics (CFD) is employed to simulate fluid flow and heat transfer processes. The results indicate that the Nusselt number (Nu) decreases by more than 50% when particle concentration reaches 7.3%, while under constant heat flux conditions Nu remains independent of the Reynolds number. As the particles concentration increases, Nu reduces significantly to a value of 2.5, beyond which the reduction follows an asymptotic trend. Additionally, an empirical correlation between Nu and the friction factor has been developed, providing a reliable predictive tool for evaluating the heat exchanger performance under scaling conditions. These findings offer valuable insights into mitigating fouling effects and minimizing performance losses due to particle deposition.